Treating a crude and natural gas stream to obtain a stabilized crude hydrocarbon stream and a gaseous stream is a well-known technique which is typically carried out in a stabilization unit. The treating step is also referred to as a stabilization process.
The stabilization process helps to make the crude liquid hydrocarbons more suitable for further processing or handling, such as safe storage and/or for shipment in tankers. The stabilization process is commonly a distillation process, designed to remove undesired compounds such as hydrogen sulphide, lighter mercaptans, lighter hydrocarbons, and for reducing vapour pressure to meet a desired specification such as a specific Reid Vapour Pressure (RVP).
Hitherto, it has always been regarded as extremely important to remove water from the crude and natural gas stream prior to the stabilization unit, and so operate the stabilization unit in a ‘dry’ mode. This is because typical temperatures used at the top and bottom of a stabilization unit prevent exit of any free water as part of the top or bottom streams. Thus, any free water accumulating in the unit results in foaming and flooding.
WO 03/022958 A1 shows a process for treating a crude containing natural gas, where the crude is first passed through a high-pressure separator to remove water as a bottom stream, followed by a low-pressure separator, and then an optional oil/water separator to further remove any water, prior to reaching an atmospheric separator and withdrawal of stabilized oil.
It is a problem with the conventional stabilization process to require CAPEX and OPEX to minimize water ingress into a stabilizer unit.